低密度NbTiAlCrSi合金显微组织及力学性能

Microstructure and Mechanical Properties of Low-density NbTiAlCrSi Alloy

采用真空自耗电弧熔炼法制备了密度为6.0g/cm3的NbTiAlCrSi合金,并通过光学显微镜、扫描电镜、能谱仪等对其进行了组织观察和分析。结果表明:合金组织由(Nb,Ti)5Si3和(Nb,X)SS两相组成(X代表Ti、Al、Cr等元素),(Nb,Ti)5Si3呈条、块状网络连续分布的特点。对合金铸锭进行1 400℃/9h均匀化退火处理不能显著改变(Nb,Ti)5Si3条、块的大小,但使得(Nb,Ti5)Si3第二相分布由连续的条、块转变为不连续的(Nb,Ti)5Si3块。该合金热轧态的抗拉强度达704MPa,室温拉伸脆断。M5Si3型化合物特性以及热轧态中第二相与基体界面处所存在的细微孔隙导致了合金的脆性。

NbTiAlSi alloy with a density of 6.0 g/cm3 was prepared by vacuum consumable arc melting,and its microstructure was observed and analyzed by using optical microscope,scanning electron microscope and X-ray energy dispersive spectrometer.The results show that the alloy microstructure is composed of the two phases of（Nb,Ti）5Si3 and（Nb,X）SS（X represents such elements as Ti,Al,Cr and so on）.（Nb,Ti）5Si3 phase presents continuous net distribution with strip and block pattern.The sizes of（Nb,Ti）5Si3 strip and block cannot be changed significantly,but the distribution of the second phase of（Nb,Ti）5Si3 changes from continuous strip and block pattern to discontinuous block pattern by 1 400 ℃/9 h homogenization annealing treatment of alloy ingot.The tensile strength of the hot-rolled alloy reaches 704 MPa,and it presents the performance of tensile brittle fracture at room temperature.The brittleness of the alloy is caused by the characteristics of the M5Si3-type compounds and the micropores existing on the interface of the second phase and substrate of the hot-rolled alloy.